• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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• pp.184-186
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• 2000

This paper proposes the introduction of TAR(Threshold Autoregressive) model for short-term load forecasting including temperature variable. TAR model is a piecewise linear autoregressive model. In the scatter diagram of daily peak load versus daily maximum or minimum temperature, we can find out that the load-temperature relationship has a negative slope in lower regime and a positive slope in upper regime due to the heating and cooling load, respectively. In this paper, daily peak load was forecasted by applying TAR model using this load-temperature characteristic in these regimes. The results are compared with those of linear and quadratic regression models.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.66-69
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• 2008

In this paper, The author present a load current feed-forward compensator by method that improve voltage controller of Step-down Chopper to get stable output voltage to sudden change of load current. To confirm the characteristicsof a presented load current feed -forward compensator compared each transfer function of whole system that load current feed-forward compensator is added with transfer function of whole system that existent voltage controller is included using Mason gains formula in Root locus and Bode diagram. As a result the pole of system is improved, extreme point of the wave and system improves, and size of peak value and phase margin of break frequency in resonance frequency confirmed that is good. Therefore, presented control technique could confirm that reduce influence by perturbation and improves stationary state and dynamic characteristics in output of Step-down Chopper.

• 소성∙가공
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• 제30권4호
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• pp.172-178
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• 2021

The cold forging process induces material deformation in an enclosed space, generating a very high forging load. Therefore, it is mainly designed as a multi-stage process, and fatigue failure occurs in forging die due to cyclic load. Studies have been conducted previously to quantitatively predict the fatigue limit of cold forging dies, however, there was a limit to field application due to the large error range and the need for expert intervention. To solve this problem, we conducted a study on the introduction of a real-time forging load measurement technology and an automated system for quantitative prediction of die life cycle. As a result, it was possible to reduce the error range of the quantitative prediction of die life cycle to within ±7%, and it became possible to use the die life cycle calculation algorithm into an automated system.

• Advances in concrete construction
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• 제14권3호
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• pp.153-167
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• 2022

The interaction between blast load and structures, as well as the interaction among structural members may well affect the structural response and damages. Therefore, it is necessary to analyse more realistic reinforced concrete structures in order to gain an extensive knowledge on the possible structural response under blast load effect. Among all the civilian structures, columns are considered to be the most vulnerable to terrorist threat and hence detailed investigation in the dynamic response of these structures is essential. Therefore, current research examines the effect of blast loads on the reinforced concrete columns via development of Pressure- Impulse (P-I) diagrams. In the finite element analysis, the level of damage on each of the aforementioned RC column will be assessed and the response of the RC columns when subjected to explosive loads will also be identified. Numerical models carried out using LS-DYNA were compared with experimental results. It was shown that the model yields a reliable prediction of damage on all RC columns. Validation study is conducted based on the experimental test to investigate the accuracy of finite element models to represent the behaviour of the models. The blast load application in the current research is determined based on the Lagrangian approach. To develop the designated P-I curves, damage assessment criteria are used based on the residual capacity of column. Intensive investigations are implemented to assess the effect of column dimension, concrete and steel properties and reinforcement ratio on the P-I diagram of RC columns. The produced P-I models can be applied by designers to predict the damage of new columns and to assess existing columns subjected to different blast load conditions.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.508-513
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• 2006

Anchor bolt in baseplate fastenings on the slab track is an important component to conform placing and safety of fastenings. Due to the way of load transmission control of fastenings, sometimes anchor bolt has to be applied lateral load. So we have to take care for it when we design. Especially, in the case of anchor bolt which is applied loads repeatedly, we have to consider fatigue failure. If parts of machine are damaged in static loads, stress will exceed the yield strength. So parts could be transformed largely. Therefore because they are visible to the naked eyes, we can replace parts before failure. However, because fatigue failure that are invisible to the naked eyes happen unexpectedly, it's very dangerous. To make a reasonable design of anchor bolts, we will analyze them by changing diameters of anchor bolt, quality of insert, initial gap between anchor bolt and insert, the presence of insert, etc. which affect the stresses of anchor bolts. We can get the maximum and minimum amplitude of stress through the modified Goodman diagram or Smith diagram which represents limit of all strengths and stress components to the average stress. We also tried to show the way of examining the expected th life of anchor bolt briefly through considering above.

• 한국압력기기공학회 논문집
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• 제16권2호
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• pp.35-46
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• 2020

In this paper, a fracture mechanics evaluation system which can be used to assess the leak-before-break (LBB) of nuclear piping is developed. Existing solutions for calculating the fracture mechanics parameters (J-integral and crack opening displacement) required for LBB evaluation were firstly presented. Then a module for calculating J-integral and COD was developed, with an additional module for predicting the critical load based on the crack driving force diagram to finally develop a fracture mechanics evaluation system. To confirm the validity of the proposed evaluation system, finite element (FE) analysis was performed, and the FE J-integral and COD results were compared with prediction results using the J-integral and COD estimations program. Furthermore, the critical load assessment module was verified by comparing the actual pipe test results (Battelle test data) with prediction results using the proposed program.

• 컴퓨터교육학회논문지
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• 제19권2호
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• pp.99-114
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• 2016

일시적 정보효과는 멀티미디어 학습 환경에서 길고 복잡한 청각적 정보의 일시성으로 인해 학습에 가해지는 부정적인 효과를 말한다. 본 연구는 인지부하이론의 틀에서 멀티미디어 학습에서 일시적 정보효과가 학습에 미치는 영향을 살펴보고, 또한 일시적 정보효과를 극복하는 방법인 것으로 생각되는 분절화(long vs. short)와 학습자료 제시 조절방법(system-paced vs. learner-paced)이 일시적 정보효과에 어떤 영향을 미치는 지 살펴보고자 하였다. 연구결과에 의하면 멀티미디어 학습 환경에서 길고 복잡한 학습자료를 학습자에게 제시할 경우에는 시각적으로만 제시하는 것이 시청각적으로 제시하는 것보다 학습효율성이 보다 높은 것(높은 성취와 낮은 인지부하 투입)으로 드러났다. 또한 시청각적으로 자료를 제시해야 하는 경우는 청각적 학습 자료를 분절화해서 제시하거나, 학습자료 제시를 학습자가 조절하는 방법으로 멀티미디어 학습 환경을 설계하는 것이 학습 효율성을 높이는 방안인 것으로 드러났다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.85-91
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• 2000

The smallest value of the load when the equilibrium condition becomes to be unstable is defined as the buckling load. The primary objective of this paper is to analyse stability boundaries for star dome under combined loads and is to investigate the iteration diagram under the independent loading parameter In numerical procedure of the geometrically nonlinear problems, Arc Length Method and Newton-Raphson iteration method is used to find accurate critical point(bifurcation point and limit point). In this paper independent loading vector is combined as proportional value and star dome was used as numerical analysis model to find stability boundary among load parameters and many other models as multi-star dome and arches were studied. Through this study we can find the type of buckling mode and the value of buckling load.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.585-590
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• 2001

Turbine blade is subject to torsional load by torsion-mount, centrifugal load by rotation of rotor and repeated bending load by steam pressure. Turbine with partially cracked blade has normal working condition at initial repair time but vibratory working condition at middle repair time due to crack growth. Finite element analysis on turbine blade indicates that repeated bending load out of all loads is the most important factor on fatigue strength of turbine blade. Therefore, this study shows root mean square roughness has linear relation with stress intensity factor range in 12% Cr steel and can predict loading condition of fractured turbine blade.

• 한국자동차공학회논문집
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• 제9권6호
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• pp.170-177
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• 2001

Turbine blade is subject to torsional load by torsion-mount, centrifugal load by rotation of rotor and repeated bending load by steam pressure. Turbine with partially cracked blade has normal working condition at initial repair time but vibratory working condition at middle repair time due to crack growth. Finite element analysis on turbine blade indicates that repeated bending load out of all loads is the most important factor on fatigue strength of turbine blade. Therefore, this study shows root mean square roughness has linear relation with stress intensity factor range in 12% Cr steel and can predict loading condition of fractured turbine blade.